Device for dewatering mud, sludge or fibre suspensions

ABSTRACT

A dewatering device for mud, sludge or fibre suspensions having a feeder screw mounted for rotation in a perforated drum in which the feeder screw feeds the mass to be dewatered from an inlet opening to an annular outlet opening having a conical flow regulator for defining the effective size of the outlet opening, and including means for imparting rotational movement of the flow regulator about the axis of the drum against the rotational direction of the feeder screw during a portion of the cycle of screw rotation.

United States Patent inventor Tad Glowacki Hembergavagen 3, Toby, Sweden Appl. No. 768,298 Filed Oct. 17, 1968 Patented Jan. 19, 1971 Priority Nov. 10, 1967 Sweden DEVICE FOR DEWATERING MUD, SLUDGE OR FIBRE SUSPENSIONS 5 Claims, 4 Drawing Figs.

[15. Cl 100/148, 100/45 Int. Cl. 1330b 15/32 Field of Search 100/ 147, 148, 43, 45

[56] References Cited UNITED STATES PATENTS 3,246,594 4/1966 Fisher 100/14'7X 3,370,527 2/1968 Holbrook l00/l47 3,432,344 3/1969 Farmer 100/147X Primary ExaminerEdward L. Roberts Attorney-Burns, Doane, Swecker and Mathis ABSTRACT: A dewatering device for mud, sludge or fibre suspensions having a feeder screw mounted for rotation in a perforated drum in which the feeder screw feeds the mass to be dewatered from an inlet opening to an annular outlet opening having a conical flow regulator for defining the effective size of the outlet opening, and including means for imparting rotational movement of the flow regulator about the axis of the drum against the rotational direction of the feeder screw during a portion of the cycle of screw rotation.

PATENTEB JAN] 91971 SHEET 0F 4 m. M m m a 9A. M g M B 6 D IKmN DEVICE FOR-DEWATERING MUD, SLUDGE R FIBRE SUSPENSIONS The present invention relates to a device for dewatering i mud, sludge or fibre suspension, comprising a feeder screw 7-, which is rotatable in'a perforated drum enclosing said screw,

ty, and in such devices knots or plugs are easily formed in the outlet opening.

a it is known to provide conical flow regulators in such devices, said'flow regulators being locatedin frontof the outlet openingwith the point of the cone directed against said opening, thecone being pressed towards the opening by spring action, in order to controlthe quantity and the humidity of the dewatered pulp.

In such devices, however, plugs or knots are easily formed at one place betweenthe rim of the outlet opening and the wall surface of the flow regulator. When such plugs or knots are formed, the flow regulator can not perform its controlling movement, which means that much too wet pulp will be fed out at such places of the outfed opening where the plug is not located.

An object of the present invention is a device for eliminating said drawback.

The present invention relates to a device for dewatering mud, sludge and fibre suspensions, comprising a feeder screw which is rotatable in a perforated drum enclosing said screw,

an inlet openingfor suspension, and an outlet opening for dewatered pulp, anda conical flow regulator for dewatered pulp located in front of the outlet opening, said flow regulator limiting the size of the outlet opening and being located at an adjustable distance from the outlet opening and being preferably pressed by a spring force in a direction towards the outlet opening, said springforce being preferably generated by a hydraulic or a pneumatic device.

The invention is generally characterized by the fact, that the flow regulator is connected to driving means, said driving means giving the flow regulator a rotating movement in a rotational direction opposite to the direction of rotation of the feeder screw, at least during a part of the time the screw is rotating.

in the following, the invention will be described with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation, partly in section, of a dewatering device accordingtothe invention. r

FIG. 2 is an end viewyof the same device as seen from the outlet opening thereof. 1 H0. 3 is a top view of the device according to FIG. 1.

FIG. 4 is a side elevation of a modified dewatering device according to the invention.

in the drawings, 1 designates the outer end of a feeder screw, said end being located close to an outlet opening for dewatered pulp. 2 designates an inlet opening for mud, sludge or fibre suspensions which should be dewatered, and 3 designates said outlet opening for dewatered pulp. The feeder screw 1 is surrounded by a perforated drum 4which encloses the screw, and in which the mud is guided during its transport from the inlet opening 2 to the outlet opening 3, and through the perforations of which the liquid which is pressed out of the pulp due to the action of the feeder screw, flows away. The outpressed liquid flows through a special outlet opening 5. The drum 4 is supported in a housing ti which together with the drum is adjustable in a longitudinal direction in relation to the feeder screw bymeans of special adjusting means 7 and 8. Said adjusting means 7 and 8 are preferably hydraulically or pneumatically controlled. By said adjusting means 7 and 8 the size of the outlet opening for dewatered pulp, can easily be controlled.

or hydraulic cylinder 11. The interior of said cylinder is connected to a closed air compression-chamber or the like, so that the flow regulator 9 is pressed towards the outlet opening by spring pressure. The rod 10 of the flow regulator is rotatably pivoted in a bearing 12. An arm 13 is fastened to the rod 10. The outer end of said arm 13 is carrying a rod 14 which extends parallel to the rod 10 and is connected to the flow regulator as illustrated at 15. The rod 10 is embraced by a forkshaped member 16 (see FIG. 2), which is mounted on a bracket 17. The bracket 17 carries a pneumatic or hydraulic cylinder 18 which is reciprocally slidable on a piston rod 19 which is' provided with a piston (not shown) inside the cylinder 18. inlet and outlet openings for a pressure fluid, for example air, are arranged on the cylinder 18 so that the cylinder by means of pressure fluid which is supplied to said openings will perform a reciprocal movement on the rod 19. The flow regulator 9 is further provided with a number of ribs 21 (F IG. I). Said ribs 21 may consist of rectangular steel rods welded to the mantle surface of the flow regulator and having a cross-sectional size of, for example, 10 mm. width and 5 mm. height.

The operation of the device is as followsrWhen mud, sludge or fibre suspension is fed into the inlet opening 2, said suspension will be transported by the rotating screw 1 towards the outlet opening, and during this movement liquid is pressed out of said suspension. The dewatered pulp is fed out at the outlet opening beyond the outer end of the screw 1. The humidity of the pulp is depending of the size of the outlet opening. The size of the outlet opening is determined by the location of the flow regulator 9 in relation to the drum 4. The outlet opening is constituted by the annular space between the flow regulator 9' and the edges of the opening in the drum 4.

Because the flow regulator is pressed by spring pressure towards the outlet opening 3, an automatic control to a certain degree of the dryness of the fed-out pulp is obtained. if the pulp tends to be drier, the flow regulator is pressed rearwards in front of the outlet opening there is a conical flow regulator 9, the outer mantlesurface of which is directedagain'st said outlet opening 3. The flow regulator 9 is carried by a rod 10, which is adjustable in its longitudinal direction by a pneumatic and, consequently, the outlet opening is increased in size, which in turn leads to the pulp being more easily fed out, so that the degree of humidity increases.

This function is, however, unreliable. in certain kinds of pulp it occurs that plugs or knots are formed which get struck unsymmetrically in the outlet opening 3 and which prevent the automatic movements of the flow regulator 9. if such a plug of sufficient size is formed at one side of the outlet opening, this means that in other places of the outlet opening, said outlet opening is rather big and not controlled. Through this big opening, pulp which is incompletely dewatered or not at all dewatered can be fed out.

Now, according to the invention the flow regulator 9 performs a rotational reciprocating movement during the feeding out of pulp, said movement being imparted to the flow regulator by the cylinder 18 and the piston rod 19, and by pressure medium fed to said cylinder and exhausted therefrom. Because of this movement of the flow regulator, plugs or knots which tend to form in the outlet opening are immediately dissolved. Therefore, the pulp is fed out evenly and uniformly through the whole outlet opening 3. Thereby the flow regulator is not prevented to function in the intended way for regulating the size of the outlet opening and controlling the dryness of the cutfed pulp.

Though it is advantageous to let the flow regulator 9 perform a reciprocal rotational movement and especially advantageous to let the movement be rather quick when it is in the same rotational direction as the screw and slower when the rotational direction is opposite to that of the screw, very satisfactory results are obtained if the flow regulator performs its movement at equal rotational speed in both directions. The angular velocity of said movement should preferably be lower than the angular velocity of the rotational movement of the screw 1.

instead of letting the flow regulator 9 perform a reciprocating movement it will, however, be possible to obtain rather satisfactory results by letting the flow regulator rotate in'one direction in relation to the outlet opening 3. Also in that case it is advantageous to let the flow regulator rotate at another angular velocity than that of the screw. The flow regulator 9 should in this case be rotated opposite to the rotational direction of the screw but rather good results are also obtained, when the flow regulator rotates in the same direction as the screw.

In HO. 4 an embodiment of the invention is illustrated in which an instrument casing 22 is mounted in front of the cylinder 11. This instrument casing 22 includes among others the necessary apparatus for supplying pressure medium to the cylinders 11 and i8 and some automatically functioning device for the cylinder 18 to perform its reciprocating movement on the piston rod 19. Said device may comprise a constantly running motor which is mechanically connected to valves for periodically supplying pressure medium to the openings in the wall of said cylinder 18 and for periodically letting out such pressure medium therefrom. The side of the instrument casing 22 which is remote from the cylinder 11 is preferably a control panel and provided with manually actuatable control means for the starting and the stopping of the machine and for other control of the machine as well as with instruments by means of which for example the pressure of the pressure medium in one or more points of the pressure system may be measured and controlled.

Other embodiments of the invention may be made within the scope of the appended claims.

lclaim:

l. in a dewatering device having a feeder screw, a perforated drum enclosing the screw. means for rotating the feeder screw within said drum, an inlet opening for introducing a suspension'into one end of the drum, an outlet opening at the other end of the drum for dewatered pulp, a conical flow regulator disposed coaxially with the drum in front of the outlet opening for defining the effective size of the outlet opening, means for varying the position of the regulator along the axis of the drum, and means for biasing said regulator towards the outlet opening, the improvement comprising flow regulator driving means connected to impart rotational movement of the axis of said flow regulator about the axis of said drum, said rotational movement being against the rotational direction of the feeder screw during a part of the cycle of screw rotation.

2. A device according to claim 1 wherein said driving means includes means for reversing the rotational movement of the flow regulator with respect to the rotational direction of the screw during another part of the cycle of screw rotation.

3. A device according to claim 2 wherein the direction of rotation of said flow regulator is reversed after rotating over an angle between about 75 and l 10.

4. A device according to claim 1 wherein the direction of rotation of said flow regulator is reversed after rotating over an angle between about 75 and 1 10.

5. A device according to claim 4 wherein said flow regulator is mounted on a rod, and wherein said driving means includes a reciprocating device, a connecting member coupled to said reciprocating device and having a slot in one end thereof, and an arm connected at one end to said rod and having a stud carried by the other end of said arm in engagement with said slot. 

2. A device according to claim 1 wherein said driving means includes means for reversing the rotational movement of the flow regulator with respect to the rotational direction of the screw during another part of the cycle of screw rotation.
 3. A device according to claim 2 wherein the direction of rotation of said flow regulator is reversed after rotating over an angle between about 75* And 110*.
 4. A device according to claim 1 wherein the direction of rotation of said flow regulator is reversed after rotating over an angle between about 75* and 110*.
 5. A device according to claim 4 wherein said flow regulator is mounted on a rod, and wherein said driving means includes a reciprocating device, a connecting member coupled to said reciprocating device and having a slot in one end thereof, and an arm connected at one end to said rod and having a stud carried by the other end of said arm in engagement with said slot. 